Inter-cultivar and temporal variation of phenolic compounds, antioxidant activity and carbohydrate composition of pecan (Carya illlinoinensis) kernels grown in Tunisia

This research aimed to study the influence of crop year and cultivar on the composition of phytochemicals and carbohydrates of pecan (Carya illinoinensis) kernels. Three pecan cultivars, Mahan, Moore and Burkett, grown at the same location, were analyzed for their total phenols, total flavonoids, total flavanols, total condensed tannin, total o-diphenols, HPLC phenolic profile, antioxidant activity, and carbohydrate composition over two harvest years. Five individual phenolic compounds were identified and quantified in pecan kernels: gallic acid, catechin, epicatechin, an ellagic acid derivative and ellagic acid. Mahan exhibited the highest content of total phenolics, flavonoids, flavanols and condensed tannins, as well as the highest antioxidant activity among the cultivars. Significant positive correlations were found between antioxidant activity and the concentration of phenolic compound in the kernels. Based on principal component analysis performed using all the measured variables, Mahan and Burkett cultivars were clearly distinguished, while Moore presented similar characteristics to both of them. The present findings showed that phytochemicals and carbohydrates varied significantly among the cultivars and harvest years. As there is little information on the phytochemical profile of pecan nuts, the information provided here will be valuable for a better understanding of their potential contribution to health promotion and disease prevention.